GPS Signal Correlation Processing Acceleration
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Solution Overview
Problem
Conventional GPS receivers face challenges in rapidly acquiring GPS signals, especially in weak signal environments, due to hardware complexity and energy consumption issues when increasing the number of parallel correlator channels or processing rates.
Innovation Solution
A method and apparatus that digitize GPS signals at a first rate, store samples in memory, and read them at a faster second rate to generate signal replica samples for correlation processing, utilizing a Fast Fourier Transform (FFT) for incoherent accumulation and comparison against a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of parallel correlator channels is increased to accelerate GPS signal processing, then the signal acquisition speed is improved, but the hardware complexity and energy consumption increase proportionally
Solution Approach 1:
The patent segments the correlation processing into two distinct stages: a first correlation stage that processes all frequency bins in parallel across multiple channels, and a second correlation stage that focuses computational resources only on candidate frequency bins identified from the first stage. This segmentation eliminates the need to maintain all correlator channels at full processing power simultaneously, thereby reducing hardware complexity while preserving rapid signal acquisition capability.
Solution Approach 2:
The patent implements dynamic resource allocation where the number of active correlator channels is adjusted based on signal detection needs. After the first correlation stage identifies candidate frequency bins, the system dynamically reconfigures the correlator channels to focus processing power only on those candidates in the second stage. This dynamic adaptation allows the system to achieve fast initial acquisition with fewer active channels, reducing overall hardware complexity and energy consumption.
2Loss of time
If the processing rate is increased to accelerate signal search, then the time to acquire weak signals is reduced, but the energy consumption and hardware requirements increase
Solution Approach 1:
The patent applies partial action by performing complete correlation processing only on a subset of frequency bins (candidates) rather than all possible frequency bins. The first correlation stage performs a broader search, and the second stage performs detailed processing only on promising candidates identified from the first stage. This approach achieves rapid signal acquisition by concentrating computational resources on the most likely signal locations, thereby reducing overall energy consumption while maintaining fast time-to-first-fix.
3Reliability
If more correlator channels are used to improve signal acquisition in difficult environments, then the reliability of signal detection is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent performs preliminary correlation processing in the first stage to identify candidate frequency bins before committing to full correlation processing. This preliminary action filters out non-candidate frequency bins early, allowing the system to achieve reliable signal detection in difficult environments by thoroughly examining only the most promising candidates in the second stage, rather than expending full processing power on all frequency bins simultaneously. This reduces power consumption while maintaining detection reliability.
Data Source
AI summary
A method of increasing speed of digital correlation processing in a global positioning system (GPS) receiver and associated receiver. The method comprises steps of digitizing a received GPS signal at a first rate to obtain digitized samples, storing the digitized samples in a memory at the first rate, reading packs of a predetermined number of digitized samples at a second rate that is faster than the first rate, generating packs of the predetermined number of signal replica samples at the second rate, and correlating the packs of digitized samples from the memory with the generated replica samples at the second rate.